• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1412-1422
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• 2016

Austenitic stainless steels (ASSs) are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs) were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.

• Proceedings of the Technology Innovation Conference
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• 2002.02a
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• pp.59-89
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• 2002

The rapid diffusion of information and telecommunication (IT) technologies during the recent decennia produced fundamental changes in the economic activity at a global level, resulting in what became coined as the "new economy". However, empirical evidence on the contribution of IT equipment to growth and productivity is at best mixed, with the more or less consistent results on the positive link between the two relating to the United States in the 1990-s. Although the empirical literature on the link between IT investment and economic performance employs a wide variety of methodologies, the overwhelming majority of the studies appears to be employing the assumption of linearity of the IT-performance relationship and predominantly explores the direct nature thereof. In this study we relax both these assumptions and find that the indirect, or aggregate productive efficiency, effects of IT investment are as important as are the direct ones The estimated non-linear nature of the indirect relationship between IT investment intensity and productive efficiency accommodates the concepts of critical mass and complementary (infrastructure) capital offered in the literature. Our key finding is that the world economy′s average level of IT investment intensity remained below the estimated critical mass. Since in this study we developed a methodology that allows one to explicitly measure the critical mass of IT investment intensity, its individual estimation at a country or industrialsector level may help evaluate the extent to which IT investment activity has to be encouraged or discouraged.

• Progress in Medical Physics
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• v.33 no.3
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• pp.25-35
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• 2022

Purpose: Planning for radiotherapy relies on implicit estimation of the probability of tumor control and the probability of complications in adjacent normal tissues for a given dose distribution. Methods: The aim of this pilot study was to reconstruct dose-volume histograms (DVHs) from text files generated by the Eclipse treatment planning system developed by Varian Medical Systems and to verify the integrity and accuracy of the dose statistics. Results: We further compared dose statistics for intensity-modulated radiotherapy of the head and neck between the Eclipse software and software developed in-house. The dose statistics data obtained from the Python software were consistent, with deviations from the Eclipse treatment planning system found to be within acceptable limits. Conclusions: The in-house software was able to provide indices of hotness and coldness for treatment planning and store statistical data generated by the software in Oracle databases. We believe the findings of this pilot study may lead to more accurate evaluations in planning for radiotherapy.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2007.04a
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• pp.467-470
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• 2007

A golf course provides comfortable leisure space, but construction of it demands eco-friendly design which minimizes the environmental spoil and harmonizes its surroundings. Therefore, it is highly recommended that appropriate understanding of existing golf course, accurate estimation of new golf course design and precise construction. In this study, data for golf course design were researched using LiDAR intensity. Consequently, a sectional registration data of a golf course was generated efficiently.

• Journal of the Korean Data and Information Science Society
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• v.25 no.1
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• pp.169-176
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• 2014

Counting processes are widely used in many fields, whose properties are determined by the intensity function. For estimation of the parameters of the intensity functions when the process is observed continuously over a fixed interval, the likelihood function is of interest. However in the literature there are only heuristic derivations and some results are not coincident. We thus in this note derive the likelihood function of the counting process in a rigorous way. So this note fill up a hole in derivation of the likelihood function.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.2210-2214
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• 2009

This paper summarizes progress on work under the Asian Pacific FRIEND(Flow Regimes from International Experimental and Network Data - APFRIEND) initiative of the International Hydrological Programme (IHP) of the United Nations Educational, Scientific and Cultural Organisation (UNESCO) from 2005 to 2009. The results of initial work on Rainfall Intensity Duration Frequency (IFD) have just been published as a volume by UNESCO. The results of work to date is concisely presented and observations made about lessons learnt on how to successfully integrate work from nine diverse countries with differing approaches to both hydrology and water resource management structures and on some possible directions for future work.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.79-82
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• 2002

Three-dimensional pipe flows with elbows and tees for few different pipe fittings are calculated to estimate the effect of swirling flow on measuring accuracy of orifice flow meter. It is evaluated how the pressure difference across the orifice is dependent on the length of upstream straight pipe in a branch and how swirl intensity, swirl angel and axial velocity distribution affect the measuring error of orifice flowmeter. From the results, it is found that, regardless of flow rate specified in this calculation, the effect of the straight pipe length can be neglected for the lengths larger than thirty diameters although there still remain significant swirl at the orifice

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.11
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• pp.1013-1020
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• 2007

In this paper, the predictions and measurements of sound transmission loss(STL) are discussed for various types of acoustical materials and carpets. Random incidence sound transmission losses are measured by the sound intensity method. The in-house software HONUS2005 is used to predict TL and estimate the various physical properties such as the flow resistivity, the structure factor, the porosity, the Possion's ratio, and etc. After this estimation, various multi-layered materials with a steel plate are measured and predicted. In particular, Carpets are assumed to be membranes to predict acoustical performance. To confirm this assumption, double and triple-layered cases are also observed including two different kinds of carpets.

• Journal of Industrial Technology
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• v.30 no.B
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• pp.91-98
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• 2010

Recently, there has been enormous damage due to river floodings caused by localized heavy rains. The direct discharge triggered by those torrential rains inflicts severe property damage on the residents of nearby areas. To minimize the possibility of river floodings in case of heavy rains and to predict the possible damage, the management of existing rainfall and water level observatories should be checked and prediction methods based on the characteristics of water usage and floodgate of nearby rivers must be further analyzed. Therefore, this research analyzed the water level change predictions on different spots with a regression equation of rainfall and water levels, using the observation data of the water level observatory in Jeongseon-gun, Gangwon Province and the rainfall observatory which are located on the upper region of the Han river.

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.243-245
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• 2004

Failure mechanisms of weldments under fatigue loads are interpreted that multiple collinear surface cracks initiating along weld toe propagate under the mutual interaction and coalescence of adjacent two cracks. To estimate fatigue crack propagation life for these weldments, the stress intensity factors of the multiple surface cracks have to be calculated which are influenced strongly by the geometrical complexity of weld toes and attachments. The Ak-factors derived by a parametric study can be introduced for the effective calculation of the stress intensity factors taking into account the geometrical complexity. The fatigue life was estimated by using the Ak-factors and the method considering the propagation mechanisms of the multiple surface cracks. The estimated values showed a good agreement with the measured fatigue life experimentally.